When recording on a magnetic tape, an audio signal selected from various program sources, it is necessary to adjust the level of an input audio signal in such a manner that the dynamic range of a recording magnetic tape is effectively used. Some conventional tape recorders, therefore, include automatic gain control (AGC) circuits to automatically adjust the level of the input signals prior to recording. However, such a conventional automatic gain control circuit is apt to reduce the dynamic range of the input signal to an extent which is unnatural. Therefore, the conventional automatic gain control circuit is not suitable for recording audio signals, such as music signals, which are required to be recorded and reproduced faithfully. In other words conventional gain control circuits which have been used in tape recorders hitherto are disadvantageous for recording music signals and the like.
Hence, when it is intended to record music signals and the like, the level of the tape recorder input signal has to be manually adjusted, without using such an automatic gain control circuit, so as to be within the dynamic range of a recording tape on which the input signal is to be recorded. The level of the input signal is typically adjusted by manipulating a variable resistor while watching a VU meter of the tape recorder to enable visual monitoring of the adjustment. This is of course troublesome and time consuming and therefore, an inherent drawback to the prior art or conventional arrangement.